1. Field of the Invention
This invention relates generally to a prosthetic eye, and, more particularly to an improved ocular replacement apparatus that provides for magnetic coupling of a prosthesis to an implant without the use of a post or other protruding structure, and allowing the conjunctiva tissue to be closed, thereby reducing the likelihood of irritation, infection and/or rejection of the implant.
2. Description of the Related Art
There are instances where an eye has become damaged due to trauma or disease wherein it is necessary to remove the entire eyeball from the eye cavity. Thereafter, a prosthetic eye may be replaced in the eye cavity to provide a cosmetically acceptable appearance, to reduce the psychological trauma associated with loss of an eye and to correct any medical problems associated with the loss of an eye.
Presently, the most accepted medical procedures for the removal of a diseased natural eye is to perform either an enucleation or an evisceration. Generally, enucleation involves first sedating the patient and anesthetizing the eye. The attaching ocular muscles and tissues are then dissected completely away from the patient""s diseased natural eyeball. The conjunctiva and Tenon""s capsule are incised down to the sclera as close as possible to the cornea. The extra ocular muscles are disinserted at the point of their insertion on the sclera. The optic nerve is severed and the natural eyeball is removed. While controlling bleeding, a porous plastic or coral ball-shaped implant is inserted into the eye cavity. Thereafter, the ocular muscles are sutured to the exterior, porous surface of the implant, or a homologous or autologous material wrap, in accordance with their correct anatomical positions. Once muscle attachment is completed, the Tenon""s capsule and conjunctiva are closed up over the implant.
There are some instances where it is desirous to perform an evisceration rather than an enucleation of the eye. Evisceration can be performed for treatment of a blind painful eye if a rapid, less traumatic surgery, as compared to enucleation. In particular, evisceration may be desirable for old or very ill patients in whom general anesthesia is a risk. Generally, evisceration involves undermining the conjunctiva with scissors that the sclera around the limbus is free of conjunctiva. A keratome entry through the limbus into the anterior chamber of the eye is performed and curved corneal scissors is used to excise the entire cornea. An evisceration spoon is used to remove the intraocular contents while the glove is fixed by holding onto the limbal sclera with toothed forceps. Thereafter, the scleral shell is opened with forceps and the uveal tissue is scraped from inside the eye using a gauze square held in a hemostat. Bleeding is controlled by cautery. The implant can then be inserted within the cavity and, thereafter, the scleral shell is closed. The ocular muscles remain in tact and, in most cases, the patient has full mobility of the ocular globe.
In either an enucleation or an evisceration, the patient is measured for a cosmetic prosthesis after a healing period of approximately two months. After another four to six months, the prosthesis is integrated with the implant. At present, the most common method to fully integrate the prosthesis with the implant involves the use of a coupling post. To fit the post to the implant, the conjunctiva is incised and pulled partially apart to expose an anterior portion of the implant. A hole is then drilled approximately 5-7 mm deep into the implant, perpendicular to the anterior surface. The coupling post is then inserted and anchored within the hole so that an exposed end portion of the post protrudes approximately 2 mm beyond the conjunctiva. The conjunctiva is then pulled closed around the base of the post over the anterior surface of the implant. A hole or other means on the inner surface of the prosthesis receives the protruding end of the post so that the prosthesis remains attached to the post. Hence, as the muscles of the eye move the implant, the coupling post serves to move the prosthesis with the implant to simulate natural eye movement.
While the above-described procedure is the most effective method presently known to couple a prosthesis to an eye implant, patients have experienced numerous problems with this technique. Specifically, fully integrated prosthetic implant devices have been disappointing in the past because of associated complications, such as extrusion of the implant and conjunctival erosion. In some instances, movement of the prosthesis and coupling post relative to the conjunctiva has caused extreme irritation to the conjunctiva tissue, resulting in infection and rejection of the implant.
Various ocular replacement systems using magnetic coupling between the implant and prosthesis have been proposed in the related art. Examples of such systems are found in the U.S. patents to Jacob-LaBarre, U.S. Pat. No. 5,192,315 and Morrell, U.S. Pat. No. 2,637,043. In these ocular replacement systems, the implant includes a protruding structure (e.g., a post) which extends outwardly through the conjunctiva. A magnet is fitted to the end of the protruding structure for direct, mating attachment with a corresponding magnet fitted to the rear side of the prosthesis. As mentioned above, movement of the protruding structure relative to the conjunctiva causes irritation to the tissue. Furthermore, the open conjunctiva permits entry of bacteria and other microorganisms into the eye cavity which can lead to infection and rejection of the implant.
Accordingly, there is an urgent need in the related field for an improved ocular replacement system and method to more effectively couple a prosthesis to an eye implant so that the likelihood of irritation, infection and/or rejection of the implant is minimized and the need of a second surgical procedure is eliminated. Moreover, there is an urgent need for an ocular replacement system and method which allows for prosthetic eye movement using a magnetic coupling system, wherein the magnetic attraction is through the conjunctiva tissue, without disrupting the conjunctiva, thereby enabling the conjunctiva to be fully closed in a manner which prevents irritation and possible infection.
Generally, in accordance with the present invention, an apparatus for use in replacing the natural eye of a patient in an eye cavity is provided. More specifically, the present invention provides an ocular replacement system including a ball-shaped implant body sized and configured for receipt within the eye cavity and having an anterior surface positioned forwardly within the eye cavity to create a semi-spherical shape which is covered by the conjunctiva, and a prosthesis having an inner concave surface shaped to conform generally to the anterior surface of the implant and the covering conjunctiva.
In accordance with the system and method of the present invention, an improved means of coupling the prosthesis to the implant is provided, wherein one or more magnets are fitted to the rear concave side of the prosthesis for alignment with correspondingly positioned magnets or magnetically attractive elements fitted to the anterior surface of the implant. More particularly, magnets are fitted to both the prosthesis and the implant so that only a face of the magnets is exposed. The face of the magnets on both the prosthesis and the implant is either of a positive (+) or negative (xe2x88x92) magnetic pole. In one embodiment, the magnetic poles of the exposed magnet faces on the prosthesis are opposite to the magnetic poles of the exposed faces of the magnets on the implant, so that an attractive force exists between the first magnets on the implant and the correspondingly positioned second magnets on the prosthesis. In another embodiment, the poles of the exposed faces of the magnets on the prosthesis are the same as the poles of the exposed faces of the magnets on the implant so that a repelling force exists between the second magnets on the prosthesis and the first magnets on the implant. In either embodiment, as the implant moves, the magnetic attracting or repelling forces between the first magnets and the second magnets causes the prosthesis to follow movement of the implant in a manner which simulates natural eye movement.
Accordingly, it is an object of the present invention to provide an improved ocular replacement system and method of coupling a prosthesis to an implant.
More specifically, it is an object of the present invention to provide an ocular replacement system having an improved means for magnetically coupling of a prosthesis to an eye implant without damaging and/or irritating the ocular tissue.
It is yet another object of the present invention to provide an ocular replacement system which eliminates the need for a coupling post, thereby avoiding follow-up surgery after implant surgery.
It is a further object of the present invention to provide an improved ocular replacement system and method eliminating the need for traumatic surgical procedures to cut the conjunctiva and drill into the implant to fit a coupling post to the implant.
It is still another object of the present invention to provide an improved ocular replacement system and method which significantly reduces the likelihood of tissue irritation, infection and/or rejection of the implant.
These and other objects and advantages of the present invention will be more readily apparent with reference to the following detailed description and the accompanying drawings.